What Does U0138 Mean?
Communication has been lost with the All Terrain Control Module, which manages terrain mode selection and coordinates traction control, throttle response, transmission shift patterns, and stability systems. This is found on vehicles with selectable drive modes for off-road or varied surface conditions.
Common Causes
35%
All Terrain Control Module hardware failure or software fault
25%
Wiring harness or connector damage from environmental exposure
20%
CAN bus network fault or signal interference
10%
Terrain mode selector switch or input circuit failure
10%
Power or ground circuit fault at module
Diagnostic Steps
1
Step 1: Verify power supply and ground at All Terrain Control Module using voltmeter
2
Step 2: Inspect module connector and harness for water damage, corrosion, or physical damage
3
Step 3: Test CAN bus signal voltage and waveform quality at module connector
4
Step 4: Check terrain mode selector switch operation and circuit continuity
5
Step 5: Monitor other control modules on same CAN network to isolate network vs. module issue
Estimated Repair Cost
$200 - $1,400
Parts + labor, varies by vehicle and location
Communication has been lost with the All Terrain Control Module, which manages terrain mode selection and coordinates traction control, throttle response, transmission shift patterns, and stability systems. This is found on vehicles with selectable drive modes for off-road or varied surface conditio...
The most common cause of U0138 (Lost Communication With All Terrain Control Module) is: All Terrain Control Module hardware failure or software fault
Typical repair costs for U0138 range from $200 to $1,400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle will operate in default drive mode only, losing terrain-specific optimizations. Off-road capability and traction management may be reduced in challenging conditions.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0138 to identify the root cause.
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Quick Info
Category
Network
System
Terrain Management/Drive Mode System
Difficulty
Type
Generic (SAE)
Recommended Tools
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